There's loads of talk about saddle height and why we shouldn't run our saddles too high. But what about the other end of the spectrum - going lower? I can't really see much solid rationale (in terms of performance) for why I can't reduce my saddle height but still be able to produce the same power. As far as I'm aware, the common approach by bike fitters to setting saddle height (and I'm simplifying here) is to start with a low saddle, gradually raise the saddle to the point where foot instability or pelvis instability is starting to appear, then go down 3-5mm. This seems to be based on the belief that a higher saddle is better, up to the point where instabilities creep in. What are the issues or dangers to running saddle height too low?

What is the best way and device to measure tilt? I measure the front half of the saddle (Selle San Marco 3dfx) with the app saddle adjust on my iPhone but as it has a camera bump the readings are off. Any other techniques?